When I think about American infrastructure projects in the 70s I think about all the minority neighborhoods they ploughed through and all the roads they closed during the entire construction livetime.

I don’t know how accurate that historical perception is, but if it is that is not how things are done today (thankfully). E.g. I’ve been observing the planning of ST3 in Seattle, and they indeed compromise on design all the time in order to displace as few people and businesses as possible, and they often end up with a much more expensive and much longer building times in order to allow traffic to flow (mostly) unhindered during construction. Without those constraints I bet building would be far quicker. (that being said neither of those are excuses for why it has taken over 2 years to fix the West Seattle bridge).

Interestingly those two constraints clash in the new International District/Chinatown station. One of the alternatives would displace and disrupt more minority owned businesses on the 5th Ave. while the other would disrupt traffic flow for 5-6 years on the 4th Ave. Curiously this is one of really few portions of the ST3 plan where they don’t have a preferred alternative.